8v questions, what can I get from the yard?

[mardak at cogeco.ca (Mark)]

> Sadly Mark, I don't know the answers to any of your tech questions.
I'll
> ask the guy who built the engine about it. I'm almost positive it is a
> bored out RD, either way it is a bored out 1.8L something. I was
wondering
> about the forged pistons as well, I just figured that they're better
than
> regular pistons, because, well um, they're forged and that seems to be
a
> good thing.


Usually forged pistons are installed in high boost turbo/supercharger
applications.  If the block has forged pistons installed, I would guess
that they're in there to lower the compression ratio (MUCH better than
thicker head gaskets), and have enough strength for high boost (10+
psi).  SO, my guess is that your compression ratio with those pistons
will be around or below 8:1...  I just haven't heard of many people
going through the expense and bother of installing forged pistons if
they're not lowering the compression for serious boost...  The stock
Mahle cast pistons are very good quality, and can easily handle low
boost reliably - plus a reduction in compression ratio isn't absolutely
necessary for low boost systems if you keep it mild.  It's simply not
cost effective to use forged pistons for a low boost application - your
bang for buck ratio will suck...  SO, you might want to CC a cylinder
and combustion chamber to determine your compression ratio.  If it's low
and you're not adding a turbo/supercharger you'll be disappointed with
the power output...


> I think I heard somewhere forged pistons have a bit of a gap
> in the cylinder when cold and thus burn oil for a little while until
they
>  warm up. True? If it is, then that's kind of a bummer.


Generally, yes, but not always.  I believe this is less of an issue than
in the past - if you buy a modern high quality forged pistons.  (correct
me if I'm wrong here guys...)  I'm not sure of VW applications, but a
350 we built at work a while ago was installed with very high quality
forged pistons and the clearance was only .0005" (half a thou) larger
than normal...


> Anyways, thanks
> for the info on fox vs golf manis. Hmm, swap everything to the pass
side
> or get a shop to move the cold start a little. Not a tough choice
there.


You don't need a shop to do it!  If you have a drill and bits, plus some
sandpaper you can do it...  Someone (Patrick?) has a good tech procedure
on their website...  Swapping over the fuel injection wasn't too
difficult either, if you go that route.  You have to mangle the hell out
of the lower portion of your airbox, or modify an A2 box to sit lower in
a Mk1.  The one drawback is that it's a bit of a birdsnest of hoses and
lines afterwards (and my upper strut tie bar won't fit... - oh well,
megasquirt will clean that up NICELY!)

Mark.
80 S
81 S  ABA/JH/4K